1. Field of the Invention
This invention relates to compressors and, more particularly to water ring rotary air compressors.
2. Description of the Prior Art
Rotary air compressors are well known and commonly used in the compressor art. Also well known are water ring rotary air compressors in which a water ring is provided for the purpose of sealing the compressor and acting as a pumping fluid. However, these relatively low flow water ring rotary air compressors, for example, the compressors manufactured by the Nash Engineering Co. of South Norwalk, Conn., suffer from several shortcomings. First, the prior art water ring rotary air compressors, such as the Nash compressor, were of an all metal construction. The port sleeve, which was typically bronze, was cone shaped and mated with a cone shaped bore of the rotor assembly with very close tolerances. The all metal construction, coupled with the cone shape of the sleeve and bore, resulted in the need for shimming of the port head so as to produce the desired port head clearance and avoid metal to metal contact when replacing the port head or rotor assembly during overhaul of the compressor. Such shimming was virtually impossible in the field and required precision alignment tools. It has been proposed to utilize a removable cylindrical port sleeve made from plastic material on the port head, the port sleeve mating with the bore of the rotor assembly. It was believed that the cylindrical plastic port head would be worn to proper clearance by the metal bore and would not require shimming. However, in practice, it was found that the plastic port sleeve material was worn down at an excessive rate and required replacement often.
Second, the prior art compressors lacked means for adjusting the air flow rate. As the compressors became worn, their air flow rate decreased. This variation in air flow required adjustments of the associated equipment of compensate for output differences from one compressor to another or rebuilding of the compressor to restore the original air flow.
Third, in the prior art compressors, cavitation often resulted during compressor start up under pressure.